Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 44: Poster Session II (Semiconductors; Oxides and Insulators: Adsorption, Clean Surfaces, Epitaxy and Growth; Surface Chemical Reactions and Heterogeneous Catalysis; Surface or Interface Magnetism; Solid-Liquid Interfaces; Organic, Polymeric, Biomolecular Films; Particles and Clusters; Methods: Atomic and Electronic Structure; Time-resolved Spectroscopies)
O 44.43: Poster
Mittwoch, 28. März 2007, 17:00–19:30, Poster C
Excited states of matter probed with soft X-rays — •Martin Beye1, Martin Deppe1, Alexander Föhlisch1, Franz Hennies2, Mitsuru Nagasono1, Edlira Suljoti1, and Wilfried Wurth1 — 1Institut für Experimentalphysik, Universität Hamburg, Luruper Chaussee 149, D-22761 Hamburg, Germany — 2MAX-lab, Lund University, Ole Römers väg 1, SE-22100 Lund, Sweden
Resonant soft X-ray spectroscopy allows to determine local electronic structure and binding properties of matter in all aggregate states. Here we present an investigation on crystalline silicon between room temperature and the melting point.
We measured the temperature dependence of the onset of absorption at the silicon L3 edge in fluorescence yield. We find a shift to lower photon energies with increasing temperature that we attribute to electron-phonon interactions, lattice expansion effects and a change in the electronic screening of the final state.
In RIXS (resonant inelastic X-ray scattering) at low temperatures scattering is coherent and crystal-momentum conserving and shows features related to specific points in the bandstructure. Raising the temperature, coherence is disturbed due to electron-phonon scattering. This leads to bandstructure-integrated spectra showing the density of states. Similar effects can be observed by detuning the incident photon energy relative to the resonance which changes the duration of the scattering process. Shorter scattering duration times supress electron-phonon scattering channels, thus restoring the k-conservation rule and enhancing bandmapping features.